While provoking much gnashing of teeth in political Italy, it’s people elsewhere that should really worry about Italian Prime Minister Mario Monti’s announcement that he plans to resign as soon as he can.

Mr. Monti arrived at his decision after watching a Wagner opera in Milan and going to a conference in Cannes, so he had ample opportunity to consider his international dimension.

And it’s very considerable.

When he took the reins in Rome a year ago, he inherited a to-do list from the European Central Bank and proceeded to tick off the tasks, overhauling the most sustainable public pension scheme in Europe, adding a property tax to Italy’s fiscal repertoire, tweaked the labor law to make it easier to fire workers, and ran an austerity budget aimed at eliminating the deficit by 2013.

But that was just his day job. Mr. Monti was “the Mastermind of Club Med,” the person most able to wring significant concessions from Germany and ultimately “puppet master of Rajoy, Hollande and Draghi,” says Steen Jakobsen, chief economist at Saxo Bank.

Mariano Rajoy and Francois Hollande have electoral mandates, but it was Mr. Monti — who didn’t — who helped them blunt Angela Merkel’s austerity imperative, which had Berlin trapped in its own moralistic policy warp.

European Central Bank President Mario Draghi eventually signed on, promising potentially “unlimited” support for peripheral euro-zone government debt.

Time had been won, it seemed, allowing Spain to work out from under its housing bust and Italy to work on ways to boost growth and service its €2 trillion in public debt, which together would help France from falling into a subaltern role in continental Europe’s most important relationship.

The return of Silvio Berlusconi to active politics – which triggered Mr. Monti’s exit – leaves Ms. Merkel and also European Central Bank President Mario Draghi in a delicate position.

After all, one surefire way to seriously endanger the reforms Mr. Monti began in Italy is to insist it do even more.

“If troika heavyweights like Merkel or Draghi make statements that suggest the next government will have to further raise taxes, cut pensions or deregulate labor, opinion could swing sharply against the pro-Monti coalition,” said Anatole Kaletsky of GaveKal.

Equally sure is that Mr. Berlusconi will have them in his targets. He already takes pains to identify Ms. Merkel with Italy’s rising jobless and tax rates, and won’t have forgotten the infamous ECB letter he actually asked for – presumably hoping for something different – in the summer of 2011.

Ironically, if the goal is to call Germany’s bluff – gently pointing out dodgy bank balance sheets or the rigid internal services market, for example – to pave the way for a sustainable policy solution to the euro zone’s woes, Mr. Monti was surely the man for the job.

Respected in Germany, he could chide Ms. Merkel, who many privately think practically appointed him in Rome to do just that.

Mr. Berlusconi’s attacks are likely destined to fail to have any international effect, forcing him to dig deeper into the caverns of populism for local support.

This being Rome, Mr. Monti may be hoping Mr. Berlusconi does just that, so he can himself then morph from professor into gladiator and scoop up what all opinion polls show is a vast orphaned area of moderates with no real interest in the political survivors currently identified as centrists.

With a reasonable showing there, he can either continue governing or extract strong guarantees of continuity from Italy’s center-left Democratic Party.